This paper proposes a new imaging algorithm based on a novel accurate range model to process the data acquired by Geosynchronous-Earth-orbital Synthetic Aperture Radar (Geo-SAR). The new range model, called DRM-5, is obtained from the 1-5th order Doppler parameters of spaceborne SAR. It is employed to describe the slant range of Geo-SAR during the super-long integration time. Furthermore, the two-dimensional frequency spectrum of point targets based on the new range model is derived and analyzed. An advanced Frequency Domain Algorithm (FDA) based on DRM-5 is proposed to process the data of stripmap mode Geo-SAR. The varied Doppler parameters in the cross-azimuth direction are considered in the new imaging algorithm, and the space-varied range-azimuth coupling phase term is compensated through data blocking. A simulation experiment is performed to verify the efficiency and superiority of the new algorithm, and the results show that it has a good effect on an L-band stripmap mode Geo-SAR system with azimuth resolution around 5m and 300km range swath.
2. Tomiyasu, K. and J. L. Pacell, "Synthetic aperture radar imaging from an inclined geosynchronous orbit," IEEE Trans. Geosci. Remote Sens., Vol. 21, No. 3, 324-328, 1983.
3. Guo, D., H. Xu, and J. Li, "Extended wavenumber domain algorithm for highly squinted sliding spotlight SAR data processing," Progress In Electromagnetics Research, Vol. 114, 17-32, 2011.
4. Liu, Q., W. Hong, W. Tan, Y. Lin, Y. Wang, and Y. Wu, "An improved polar format algorithm with performance analysis for geosynchronous circular SAR 2D imaging," Progress In Electromagnetics Research, Vol. 119, 155-170, 2011.
5. Curlander, J. C. and R. N. McDonough, Synthetic Aperture Radar: System and Signal Processing, 565-591, Wiley, New York, 1991.
6. NASA and JPL, , "Global earthquake satellite system: A 20-year plan to enable earthquake prediction," , JPL Document, 400-1069, March 2003.
7. Wei, S.-J., X.-L. Zhang, and J. Shi, "Linear array SAR imaging via compressed sensing," Progress In Electromagnetics Research, Vol. 117, 299-319, 2011.
8. Xu, W., P. Huang, and Y.-K. Deng, "Muti-channel SPCMB-TOPS SAR for high-resolution wide-swath imaging," Progress In Electromagnetics Research, Vol. 116, 533-551, 2011.
9. Moreira, A. and Y. Huang, "Airborne SAR processing of highly squinted data using a chirp scaling approach with integrated motion compensation," IEEE Trans. Geosci. Remote Sens., Vol. 32, No. 5, 1029-1040, 1994.
10. Eldhuset, K., "A new fourth-order processing algorithm for spaceborne SAR," IEEE Trans. Aero. Electronic Sys., Vol. 34, No. 3, 824-835, 1998.
11. Eldhuset, K., "Spaceborne bistatic SAR processing using the EETF4 algorithm," IEEE Geosci. Remote Sens. Lett., Vol. 6, No. 2, 194-198, 2009.
12. Neo, Y. L., F. Wong, and I. G. Cumming, "A two dimensional spectrum for bistatic SAR processing using series reversion," IEEE Geosci. Remote Sens. Lett., Vol. 4, No. 1, 93-96, 2007.
13. Pillai, S. U., B. Himed, and K. Y. Li, "Effect of Earth's rotation and range foldover on space-based radar performance," IEEE Trans. Aero. Electronic Sys., Vol. 42, No. 3, 917-932, 2006.
14. Zhao, B., X. Qi, D. Yu-Kai, R. Wang, and H. Song, "Accurate fourth-order doppler parameter estimation approach for geosynchronous SAR," Proc. EUSAR 2012, Nurnberg, Germany, 2012.
15. Zhao, B., X. Qi, H. Song, W. Gao, X. Han, and R. P. Chen, "The accurate fourth-order doppler parameter calculation and analysis for geosynchronous SAR," Progress In Electromagnetics Research, Vol. 140, 91-104, 2013.
16. Wu, C., K. Y. Liu, and M. J. Jin, "A modeling and correlation algorithm for spaceborne SAR signals," IEEE Trans. Aero. Electronic Sys., Vol. 18, No. 5, 563-574, 1982.
17. Davidson, G. W., I. G. Cumming, and M. R. Ito, "A chirp scaling approach for processing squint mode SAR data," IEEE Trans. Aero. Electronic Sys., Vol. 32, No. 1, 121-133, 1996.
18. Bamler, R., "A comparison of range-Doppler and wavenumber domain SAR focusing algorithm," IEEE Trans. Geosci. Remote Sens., Vol. 30, No. 4, 706-713, 1992.
19. Tan, W., W. Hong, Y. Wang, and Y. Wu, "A novel spherical-wave three-dimensional imaging algorithm for microwave cylindrical scanning geometries," Progress In Electromagnetics Research, Vol. 111, 43-70, 2011.
20. Zhang, M., Y. W. Zhao, H. Chen, and W.-Q. Jiang, "SAR imaging simulation for composite model of ship on dynamic ocean scene," Progress In Electromagnetics Research, Vol. 113, 395-412, 2011.
21. Zhao, B., X. Qi, Y. Deng, R. Wang, H. Song, and Y. Luo, "A new method of improving the accuracy of the hyperbolic range equation," Proc. IGARSS 2012, Munich, Germany, 2012.
22. Fielder, H., E. Boerner, J. Mittermayer, and G. Krieger, "Total zero Doppler steering: A new method for minimizing the Doppler centroid," IEEE Geosci. Remote Sens. Lett., Vol. 2, No. 2, 141-145, 2005.